Electric rare gas filled lamp



Oct. 22,1935; J. M, E. DE'BEAUFORT ET AL 2,018,347

ELECTRIC RARE GAS FILLED LAMP Original Filed Dec. 22. 1950 INVENTORSJean M. E. de Beaufort,

Anton Lederer,

ATTORNEY Planted 0a. '22, 1935 UNITED STATES PATENT OFFICE Eta-cram msass mm mar.

Jean Marie Edouard de Beauiort, Paris, France,

and Anton Iederer,

Vienna, Austria; Catherine Danser and General Conrad Ronda, executors oisaid Anton Lederer, deceased, assignors oi the entire right of AntonLederer,

Ernest Anton Lederer, Glen Ridge, 8. 1.

Application December :2, mo, Serial No.5,l38.

In Amtria February 22, 1930 Renewed Decr'nber 21, 1834 1 Claim. (01.ire-ml Electric rare gas filled lamps as known heretoiore areessentially oi such construction that the glass vessel containing thefilling oi rare gas, usually neon or a mixture 01' neon and helium, is

intheiormoiatubewiththeelectrodesarranged v at the ends thereoi. It asuiiiciently high voltage is applied to the two electrodes lightphenomena appear in the interior oi the vessel between the electrodeswhich light phenomena may be used ior illuminating purposes. Ii theglass vessel contains neon or a mixtlnp oi neon and helium the result isa redor orange-red light filling the tubular space between theelectrodes; and ii somemercuryisvaporized withinthetube,so that also thevapour oi mercury is excited to light shine light results. In all cases,however, it is the light phenomena appearing in the space between theelectrodes, which are made use oi ior illuminating purposes in suchpreviously known lamps. Such lamps could be operated either on direct oron alternate current and contained either cold or hot electrodes. Butheretoiore it has been possible-only to obtain either red light or bluelight, and-never both simultaneously.

According to the present invention thev envelope oi the rare gas fllledlamp is of such shape and the electrodes are arranged therein in such amanner that not only the light phenomena appearing in the space betweenthe electrodes but also those appearing around the electrode system maydevelop and be made use oi ior illuminating purposes. It. is oiadvantage in this connection to reduce the mutuardistance oithe'el'ectrodes as compared to previously known luminous tubes and toshape the lamp vessel in such a way that it surrounds the electrodesystem, preierably in all directions, at such a distance that lightphenomena may develop also outside oi the electrode system. The lightphenomena appearing in the lamp may then be influenced in a manner neverobserved beiore, by proper selection of the relations oi pressures oithe gases or gas and vapour mixtures of the lamp filling, as well as bya modiilcation oi the electric constants which come into considerationfor the operation oi the lamp so .that various effects may be produced.

To enable the invention to be clearly understood one arrangement thereoiwill now be described by way oi example withvreierence to the single :1tic iigureoi the accompanying drawing.

a globe-shaped glass bulb a the two Within electrodes 1; are arrangedsymmetrically with respect to the centre oi the bulb at a comparativelysmall distance irom each other. The electrodes'heliumandthepressureoithisraregasmixture at room temperature may beapproximately within a range oi 0.06 to 10' mm. mercury. Furthermore, inthe glass bulb a a small quantity oimercuryisintroducedsuchasintheiormoiacom pound 0i mercury, as indicatedat d, such compound being then decomposed so that when the lamp isstarted, mercury vaporizes and this vapour admixes to the rare gasfilling. The average temperature which obtains within the lamp duringoperation is about 100 to 300 C., and the pressure oi the mercury vapourthat is iormed corresponds to the temperature. Such lamps may beoperated on ordinary line voltages or on '0 even lower voltages such asabout 20 volts and the discharge current-intensity is about 0.4 to.0.5

Such lamps do not require ior opera- ,-tlon any such hisil' voltages ashave heretoiore been customary iorelectric rare gas-filled il- 35luminating'lamps.

li a lamp according-to the present invention is 'started, intense red ororange-red lighting "aureolesf are iormed around the electrodes theborders oi which aureoles are indicated in the 40 drawing in dottedlines 0, and which, in consequence oi the small electrode separationmerge into one another to iorm an almost uniiorm aureole surrounding thetwo electrodes. The boundary oi this aTureole is oi course not .clearlya defined.

The glass globe at is spaced irom the electrode system at such adistance that light phenomena may develop also in the space outside ofthe electrode system, and it has been iound that these light phenomenaoutside the electrode system may, as above mentioned, be influenced insuch a manner that the two light phenomena have difierent appearances.Ordinarily the whole space between the aureole c and the wall oi theglass bulb a gives blue light since it corresponds to the mercuryvapour, and there results in this way a light phenomenon showing a blueenvelope around an. orange-red core becoming somewhat indistinct-towardsthe exterior. The higher the pressure of the rare gas-filling, withinthe indicated limits, the smaller is the aureo'ie c surrounding theelectrodes, and with decreasing pressure it expands outwardly whilst theblue halo fills the spacebetween the aureole and the external glasswall, and is consequently pressed outwardly with decreasing pressureand. on the other hand its thickness increases towards the electrodeswhen theaureole is, so to speak, compressed with increasing pressure.

The pressure of the raregas can be diminished to such an extent that theboundary of the aur'eole advances to the neighbourhood ofthefl wall ofthe glass vessel a while the light intensity of the aureole decreasesaccordingly. and it is to beobserved that with progressive expansion ofthe aureole the light phenomena filling the glass vessel a become more ad more'white or nearly white'in appearance. The obtaining of a whiteappearance may be still further improvedby the use of a frosted ortranslucent white glass for the vessel it because this tends somewhat toequalize the differences of intensity.

In some cases the inner surface of the glass vessel a shows a bluishhalo which indicates that the white appearanceof the lamp may be due tothe fact that the orange-red core-light or aureole has to penetrate ablue envelope before emergence.

A spectroscopic examination of thiswhite light phenomenon shows lines oiall colours from the extreme red to the extreme violet, and evenultraviolet rays can be observed if the lamp vessel consists of amaterial capable of transmitting this kind of rays. The fact that thiswhite-light phenomenon is very similar to daylight is confirmed by thesubstantial preservation of the various natural colours when illuminatedby the lamp.

The demarcation between the aureole and the surrounding blue halo may bedisplaced one way or the other by modification of the electricconstants,more particularly of the current intensity, of the size of theelectrodes, of the power of emission and of other variables, and in thisway lamps with various light efiects may be produced, name- 1y lampswith an orange-red core of different size surrounded by a blue halo, orlamps emitting a white light.

The bicolour light phenomenon in such 'a lamp has its origin in the factthat'the conditions for luminous excitation (vibration) of various gasesand vapours are different and that the conditions for excitation(density of current) vary with thedistance from the electrodes. In thespace between the electrodes and in their close proximity there areconditions for excitation .which are sulficient to excite the rare gasesas well as the meramass? the mercury alone that lights. however, asshown above, to modify the conditions cury vapour to light; the lightingeffect of the neon, however, evidently prevails over that of the mercuryto such an extent that in the aureole the blue light of the mercury doesnot appear. At a greater distance from the electrode system the 5mercury alone is excited to light, and not the'rare gas and consequentlyoutside the aureole it is It is possible,

for excitati'onin the interior of the lamp by modil0 fication of therelations of pressures and of the electric constants, in such a way thateven at greater distances from the electrodes conditions for excitationof the rare gas continue so that an expansion of the rare gas lightclose to the glass 15 wall takes place and thedescribed phenomenon ofwhite'light is obtained. I

For obtaining this phenomenon of white light the pressure oi'the raregas should be between about 2 to. 5 mm. and in any case, however, below20 Therare gas-filling may consist of about from to 99% neon and aboutfrom 45% to 1% helium. Forlamps in which the bicolour lightis desired tobe clearly maintained it is advisable 25 to use a comparatively smalladdition of argon, namely about irom.' to /5 of the mixture 01 neon andhelium.

As far as the construction is concerned the lamp may be modified invarious ways from the 30 construction hereinbefore described withreference to the drawing. The mutual distance of the electrodes may beincreased so that ultimately each electrode has its own separatelyvisible wheels, and the outer shape of the glass vessel a 85 may deviatefrom the globe shape. What is im- 1 portant however is'that the wall ofthe glass vessel surroundsthe electrode system at such a distance thatthe described light phenomena can develop more or less fully outside theelectrode system. 40

We claim:-

-An electric illuminating lamp for operation on alternating current,comprising a globular bulb having a rare gas atmosphere at leastcontaining neon, a small quantity of mercury, and two coop- 45 cratingelectrodes at least one of which is adapted to be indirectly heated toelectron emission temperature and is capable of electron emission atrelatively low temperature, whereby to produce a luminous gaseousdischarge, said electrodes be- 50 ing located symmetrically in thecenter of the bulb at about 10 mm. apart, said bulb being about to mm.diameter, and the pressure of the containcd gas-being between about '2find-10 mm,

